title: Investigation of the optimal carbon-nitrogen ratio and carbohydrate-nutrient blend for mixed-acid batch fermentations.
abstract: To determine the optimal scenario for mixed-acid fermentations, an array of batch fermentations were performed that independently varied the C/N ratio (adjusted using urea) and the blend of carbohydrate (office paper) and nutrient (wet chicken manure (CM)). A blend of 93% paper and 7% wet CM (dry basis) with a C/N ratio of 37 g C(NA)/gN had the highest culture yield (0.21 g acid(produced) /g NAVS(initial)), total acid productivity (0.84 g acid(produced)/(L(liq)d)), and conversion (0.43 g NAVS(consumed)/g NAVS(initial)). Compared to a control blend of 80% paper and 20% wet CM (dry basis, no urea) the culture yield, productivity, and conversion improved 53%, 44%, and 70%, respectively. Selectivity was a strong function of C/N ratio and varied from 0.167 to 0.667 acid(produced)/g NAVS(consumed). Nitrogen supplementation with urea improves performance and reduces costs of (1) capital, (2) nutrients, and (3) downstream processing by reducing impurities from nutrient-rich wastes (e.g., manures, sewage sludge).
authors.affiliation: Texas A&M University, Department of Chemical Engineering, 624 Jack Brown Building, College Station, TX 77843, USA. AaronSmith328@gmail.com
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Smith
authors.forename: Mark T
authors.initials: MT
authors.lastname: Holtzapple
mesh_terms: D000818:Animals; D002021:Buffers; D002241:Carbohydrates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002645:Chickens; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D008372:Manure; D009584:Nitrogen / Q000737:chemistry*
chemical_list: D002021:Buffers; D002241:Carbohydrates; D008372:Manure; D002244:Carbon; D009584:Nitrogen